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The accuracy of blood glucose measurement in clinical laboratories is vital for diabetes diagnosis. Trueness Verification Plan was carried out and analyzed for evaluating the standardization of serum glucose among clinical laboratories.

The standardization of cystatin C (CysC) measurement has received increasing attention in recent years due to its importance in estimating glomerular filtration rate (GFR). Mass spectrometry-based assays have the potential to provide an accuracy base for CysC measurement. However, a precise, accurate and sustainable LC–MS/MS method for CysC is still lacking. The developed LC–MS/MS method quantified CysC by detecting signature peptide (T3) obtained from tryptic digestion. Stable isotope labeled T3 peptide (SIL-T3) was spiked to control matrix effects and errors caused by liquid handling. The protein denaturation, reduction and alkylation procedures were combined into a single step with incubation time of 1 h, and the digestion lasted for 3.5 h. In the method validation, digestion time-course, imprecision, accuracy, matrix effect, interference, limit of quantification (LOQ), carryover, linearity, and the comparability to two routine immunoassays were evaluated. No significant matrix effect or interference was observed with the CysC measurement. The LOQ was 0.21 mg/L; the within-run and total imprecision were 1.33–2.05 % and 2.18–3.90 % for three serum pools (1.18–5.34 mg/L). The LC–MS/MS method was calibrated by ERM-DA471/IFCC and showed good correlation with two immunoassays traceable to ERM-DA471/IFCC. However, significant bias was observed for immunoassays against the LC–MS/MS method. The developed LC–MS/MS method is robust and simpler and holds the promise to provide an accuracy base for routine immunoassays, which will promote the standardization of CysC measurement. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the applicability of an alternative analytical technique to the reference method for phosphorus detection in meat and meat products established by ISO 2294:1974, revised by ISO 23776:2021. When an analytical method is modified or a new one is developed and implemented, it should be validated before being accepted for routine determinations. Furthermore, it is necessary to demonstrate that the new or alternative method has good performance characteristics in comparison with the reference method. Therefore, a comparison of the performance of the alternative and the reference method should be made. In the present study, a statistical evaluation of the calibration model of the alternative method was made with data from interlaboratory studies made in five consecutive years using fifty analyses of meat and meat products. The statistical parameters evaluated over time for the calibration curve were the y-intercept and slope; correlation and linearity; analytical limits: detection and quantification; working range; and accuracy (precision and trueness). In the interlaboratory tests, the results obtained by the alternative analytical method were compared with those obtained by the reference method, and their performance in these tests was also evaluated. The results obtained by the alternative method indicated better accuracy than the reference method due to lower relative errors, more precision, and a good trueness evaluation through lower absolute values of the z-score. The study demonstrated that the phosphorus alternative method is applicable for the determination of total phosphorus in the matrix of meat and meat products. [ABSTRACT FROM AUTHOR]

Even though reliable glucose concentration measurements are essential in diagnosis and monitoring of diabetes mellitus, external quality assurance based on mandatory reference method values can only be conducted to a limited extent for measurements in whole blood. The reason is the lack of stabilized whole blood materials suitable for the application in glucose measurement devices used in near-patient testing.

In clinical pratice, tau protein measurement generally relies on immunoassays (IAs), whose major drawback is the lack of results comparability due to differences in selectivity and/or calibration. This underlines the importance of establishing a traceability chain for total tau (t-tau) measurements. The objective of this work is to develop a higher order candidate reference measurement procedure (RMP) for the absolute quantification of t-tau in cerebrospinal fluid (CSF). To calibrate the candidate RMP and establish metrological traceability to the SI units, a primary calibrator consisting in a highly purified recombinant protein was sourced. Its purity was evaluated by liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) and the protein mass fraction in solution was certified by amino acid analysis (AAA). An isotopically-labelled homologue was obtained to develop a candidate RMP by isotope dilution mass spectrometry (IDMS) for t-tau absolute quantification in CSF. Calibration blends and quality control (QC) materials were gravimetrically prepared and subjected to the same preparation workflow as CSF samples, followed by LC-HRMS analysis in Parallel Reaction Monitoring (PRM) mode. A primary calibrator has been developed and an IDMS candidate RMP has been validated for CSF t-tau. The candidate RMP was used to certify t-tau concentration in three pools of CSF (low, medium, high). The candidate RMP will pave the road towards global standardization of CSF t-tau measurements. Together with commutable Certified Reference Materials (CRMs), it will allow evaluating and improving the accuracy and comparability of results provided by IAs. [ABSTRACT FROM AUTHOR]

Street food outlets are characterised by poor microbiological quality of the food and poor hygiene practices that pose a risk to consumer health. The aim of the study was to evaluate the hygiene of surfaces in food trucks (FT) using the reference method together with alternatives such as PetrifilmTM and the bioluminescence method. TVC, S. aureus, Enterobacteriaceae, E. coli, L. monocytogenes, and Salmonella spp. were assessed. The material for the study consisted of swabs and prints taken from five surfaces (refrigeration, knife, cutting board, serving board, and working board) in 20 food trucks in Poland. In 13 food trucks, the visual assessment of hygiene was very good or good, but in 6 FTs, TVC was found to exceed log 3 CFU/100 cm2 on various surfaces. The assessment of surface hygiene using various methods in the food trucks did not demonstrate the substitutability of culture methods. PetrifilmTM tests were shown to be a convenient and reliable tool for the monitoring of mobile catering hygiene. No correlation was found between the subjective visual method and the measurement of adenosine 5-triphosphate. In order to reduce the risk of food infections caused by bacteria in food trucks, it is important to introduce detailed requirements for the hygiene practices used in food trucks, including techniques for monitoring the cleanliness of surfaces coming into contact with food, in particular cutting boards and work surfaces. Efforts should be focused on introducing mandatory, certified training for food truck personnel in the field of microbiological hazards, appropriate methods of hygienisation, and hygiene monitoring. [ABSTRACT FROM AUTHOR]

Abstract Blood glucose measurement is one of the most commonly performed clinical diagnostic tests used to monitor glycaemia in several animal diseases. Usually, these laboratory analyses are performed on blood venous samples in remote laboratories, and the results are delayed, at best. The use of portable glucometers could evidently solve many constraints but veterinary‐use glucometers are not usually available. The present study aimed to compare blood glucose levels obtained by Bionime glucometer to the reference method using glucose oxidase. Venous blood was collected from a total number of 140 healthy dogs (72 males and 68 females), of different breeds (28 German Shepherd, 27 Pitt bull, 21 Boxer, 24 Rottweiler and 40 cross‐bred dogs) and different ages (range: 3 months–14 years) for glucose measurement using the reference laboratory method. Capillary blood samples were used to conduct a glucose measurement with a human‐use glucometer. Our results revealed that there was no significant difference between the mean capillary blood glucose (CBG) measured with the human‐use glucometer (5.06 ± 0.84 mmol/L) and the mean venous blood glucose (VBG) measured with the laboratory reference method (4.90 ± 0.73 mmol/L) (p = 0.42). Similarly, there was no significant difference of the mean CBG and VBG in male dogs (5.11 ± 0.88 and 4.97 ± 0.75 mmol/L, respectively) and female dogs (5.01 ± 0.81 and 5.07 ± 0.72 mmol/L, respectively) (p = 0.73 and 0.21, respectively), and no correlation to neither age (5.43 ± 0.90 and 5.20 ± 0.70 mmol/L in 3 to 6 month‐old dogs, 5.03 ± 0.82 and 4.94 ± 0.79 mmol/L in 6 months to 1 year‐old, 4.94 ± 0.67 and 5.13 ± 0.66 mmol/L in 1 to 4 year‐old dogs; 4.88 ± 0.94 and 4.80 ± 0.75 mmol/L in dogs older than 4 years, respectively, p

The aims of this study were to determine the concentrations and elemental composition of PM10 in the village of Kotórz Mały (Poland), to analyse their seasonal variability, to determine the sources of pollutant emissions and to compare the consistency of the results obtained using different methods. Sampling and weather condition measurements were carried out in the winter (January–February) and spring (April) of 2019. Two combinations of different techniques were used to examine PM10 concentrations and their chemical composition: gravimetric method + atomic absorption spectrometry (GM+AAS) and continuous particle monitor + energy dispersive X-ray fluorescence (CPM+EDXRF). In winter, the average concentrations of PM10 measured by the GM and CPM were similar (GM 44.3 µg/m3; CPM 34.0 µg/m3), while in spring they were clearly different (GM 49.5 µg/m3; CPM 29.8 µg/m3). Both AAS and EDXRF proved that in both seasons, Ca, K and Fe had the highest shares in the PM10 mass. In the case of the lowest shares, the indications of the two methods were slightly different. Factor analysis indicated that air quality in the receptor was determined by soil erosion, coal and burning biomass, and the combustion of fuels in car engines; in the spring, air quality was also affected by gardening activities. [ABSTRACT FROM AUTHOR]

Milk is arguably natural product which contains a number of components of nutritional significance. Milk fat is an important measure of its quality because of salubrious and technological aspect of its industrial use in interest of human. This makes determination of milk fat essential. This paper gives overview of routine and reference methods used and recent trends of fat measurement in dairy industries. Comparative study of technical and commercial aspects of different methods gives the idea of its distinctive uses. Comparison of Optical techniques based on UV, VIS, and IR wavelengths give distinct analysis, also pros and cons of analytical measurement of process. Detail analysis manifests scope of improvement which gives aspiration to develop low-cost automated reference technique for milk fat. [ABSTRACT FROM AUTHOR]

Railway superstructure components are subject to impact forces caused by irregularities in the rail and wheel or variations in the support stiffness. These imperfections lead to the premature and accelerated deterioration of the track and increase maintenance costs. Generally, to mitigate these dynamic loads, elastomeric rail pads are interposed between rails and sleepers. For each track section, the pad choice is made according to its stiffness, impact attenuation and cost. In this experimental study, eight types of rail pads were characterized using two procedures from EN 13146–3. The results revealed that the rail pad material and geometry affect the impact attenuation ability of the pad and the testing procedure affect the results. It was found that the preload applied is one of the parameters that most affects the impact attenuation value. Appling a preload of 50 kN during the impact attenuation test, which is suggested by the standard, affected this parameter by ranging from between ~2 and ~ 20, depending on the rail pad. Based on these results it is considered that EN 13146–3 should be updated. [ABSTRACT FROM AUTHOR]

A collaborative interlaboratory study of the method of direct determination of volatile compounds in spirit drinks and alcoholic products was performed. The proposed method employs ethanol, the major volatile component of an alcoholic product, as an internal standard. For the experiment realization, 9 laboratories from 4 countries – Belarus, Czech Republic, Turkey, Russia – were supplied with standard solutions for gas chromatographic measurements. Five aqueous ethanol 40 % (v/v) standard solutions containing target compounds in concentrations ranging from 10 to 400 mg/L of absolute alcohol were gravimetrically prepared and delivered to the participants. The interlaboratory study was evaluated according to the ISO 5725 standards and the «EuroChem» guide. The repeatability limits (within-laboratory precision) varied between 0.4 and 7.5 % for all samples and compounds, showing a sufficiently high repeatability of the method. The reproducibility limits (between-laboratory precision) were found to vary within a satisfactory range of 0.5–10.0 %. Precision of the method was well within the range predicted by the Horwitz equation for all analytes. In the study experimental estimation of trueness was performed for the first time. Analysis of the obtained results showed that the bias of the method is insignificant at the significance level 5 %. The experimentally determined concentrations of the analytes compared well to the gravimetrical values, thus showing very satisfactory accuracy of the method. The results of the interlaboratory study confirmed that the method «ethanol as internal standard» is robust and reliable and can be used as a standard method for the determination of volatile compounds in water-ethanol samples. Moreover, this method can be validated in any one laboratory without performing additional experimental studies based on the results obtained by validation of the traditional method.

Street food outlets are characterised by poor microbiological quality of the food and poor hygiene practices that pose a risk to consumer health. The aim of the study was to evaluate the hygiene of surfaces in food trucks (FT) using the reference method together with alternatives such as PetrifilmTM and the bioluminescence method. TVC, S. aureus, Enterobacteriaceae, E. coli, L. monocytogenes, and Salmonella spp. were assessed. The material for the study consisted of swabs and prints taken from five surfaces (refrigeration, knife, cutting board, serving board, and working board) in 20 food trucks in Poland. In 13 food trucks, the visual assessment of hygiene was very good or good, but in 6 FTs, TVC was found to exceed log 3 CFU/100 cm2 on various surfaces. The assessment of surface hygiene using various methods in the food trucks did not demonstrate the substitutability of culture methods. PetrifilmTM tests were shown to be a convenient and reliable tool for the monitoring of mobile catering hygiene. No correlation was found between the subjective visual method and the measurement of adenosine 5-triphosphate. In order to reduce the risk of food infections caused by bacteria in food trucks, it is important to introduce detailed requirements for the hygiene practices used in food trucks, including techniques for monitoring the cleanliness of surfaces coming into contact with food, in particular cutting boards and work surfaces. Efforts should be focused on introducing mandatory, certified training for food truck personnel in the field of microbiological hazards, appropriate methods of hygienisation, and hygiene monitoring.

Blood glucose measurement is one of the most commonly performed clinical diagnostic tests used to monitor glycaemia in several animal diseases. Usually, these laboratory analyses are performed on blood venous samples in remote laboratories, and the results are delayed, at best. The use of portable glucometers could evidently solve many constraints but veterinary‐use glucometers are not usually available. The present study aimed to compare blood glucose levels obtained by Bionime glucometer to the reference method using glucose oxidase. Venous blood was collected from a total number of 140 healthy dogs (72 males and 68 females), of different breeds (28 German Shepherd, 27 Pitt bull, 21 Boxer, 24 Rottweiler and 40 cross‐bred dogs) and different ages (range: 3 months–14 years) for glucose measurement using the reference laboratory method. Capillary blood samples were used to conduct a glucose measurement with a human‐use glucometer. Our results revealed that there was no significant difference between the mean capillary blood glucose (CBG) measured with the human‐use glucometer (5.06 ± 0.84 mmol/L) and the mean venous blood glucose (VBG) measured with the laboratory reference method (4.90 ± 0.73 mmol/L) (p = 0.42). Similarly, there was no significant difference of the mean CBG and VBG in male dogs (5.11 ± 0.88 and 4.97 ± 0.75 mmol/L, respectively) and female dogs (5.01 ± 0.81 and 5.07 ± 0.72 mmol/L, respectively) (p = 0.73 and 0.21, respectively), and no correlation to neither age (5.43 ± 0.90 and 5.20 ± 0.70 mmol/L in 3 to 6 month‐old dogs, 5.03 ± 0.82 and 4.94 ± 0.79 mmol/L in 6 months to 1 year‐old, 4.94 ± 0.67 and 5.13 ± 0.66 mmol/L in 1 to 4 year‐old dogs; 4.88 ± 0.94 and 4.80 ± 0.75 mmol/L in dogs older than 4 years, respectively, p < 0.05), nor to breed (4.94 ± 1.01 and 4.99 ± 0.79 mmol/L in German Shepherd, 5.13 ± 0.84 and 4.99 ± 0.79 mmol/L in Pitt Bull, 5.07 ± 0.94 and 5.07 ± 0.77 mmol/L in Boxer, 5.40 ± 0.59 and 5.48 ± 0.55 mmol/L in Rottweiler and 4.89 ± 0.75 and 4.77 ± 0.59 mmol/L in cross‐bred dogs, respectively, p < 0.05). The present study confirms that human glucometer can be used to measure glucose in dogs with a good accuracy. [ABSTRACT FROM AUTHOR]

Objectives: In 2009, the Japan Society of Clinical Chemistry (JSCC) recommended a reference method for the measurement of serum high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels. This automated method uses cholesterol esterase-cholesterol dehydrogenase to measure cholesterol levels in fractions obtained after ultracentrifugation and dextran sulfate/magnesium chloride precipitation. In the present study, using fresh samples, we compared the LDL-C and HDL-C levels measured using this method with those measured using the traditional Centers for Disease Control and Prevention (CDC)-beta-quantification (BQ) method. Design: and methods: Using both the JSCC and CDC-BQ methods, LDL-C/HDL-C levels were measured in 47 non-diseased and 126 diseased subjects, whose triglyceride levels were lower than 11.29 ​mmol/L (1000 ​mg/dL). Results: For LDL-C, the equation of the line representing the correlation between the two methods was y ​= ​0.991x + 0.009 ​mmol/L; r ​= ​0.999; and Sy/x ​= ​0.025 ​mmol/L, where x is the mean LDL-C level measured using the CDC-BQ method. Similarly, for HDL-C, the equation of the line representing the correlation between the two methods was y ​= ​0.988x + 0.041 ​mmol/L, r ​= ​0.999, and Sy/x ​= ​0.019 ​mmol/L, where x is the mean HDL-C level measured using the CDC-BQ method. Conclusions: The JSCC method agreed with the CDC-BQ method in cases of both non-diseased and diseased subjects, including those with dyslipidemia.

BACKGROUND: A robust proxy for estimating methane (CH4) emissions of individual dairy cows would be valuable especially for selective breeding. This study aimed to improve the robustness and accuracy of prediction models that estimate daily CH4 emissions from milk Fourier transform mid‐infrared (FT‐MIR) spectra by (i) increasing the reference dataset and (ii) adjusting for routinely recorded phenotypic information. Prediction equations for CH4 were developed using a combined dataset including daily CH4 measurements (n = 1089; g d−1) collected using the SF6 tracer technique (n = 513) and measurements using respiration chambers (RC, n = 576). Furthermore, in addition to the milk FT‐MIR spectra, the variables of milk yield (MY) on the test day, parity (P) and breed (B) of cows were included in the regression analysis as explanatory variables. RESULTS: Models developed based on a combined RC and SF6 dataset predicted the expected pattern in CH4 values (in g d−1) during a lactation cycle, namely an increase during the first weeks after calving followed by a gradual decrease until the end of lactation. The model including MY, P and B information provided the best prediction results (cross‐validation statistics: R2 = 0.68 and standard error = 57 g CH4 d−1). CONCLUSIONS: The models developed accounted for more of the observed variability in CH4 emissions than previously developed models and thus were considered more robust. This approach is suitable for large‐scale studies (e.g. animal genetic evaluation) where robustness is paramount for accurate predictions across a range of animal conditions. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to verify the analytical performance of four homocysteine detection systems made in China and to explore the comparability of homocysteine detection systems by isotope dilution liquid chromatography- tandem mass spectrometry (ID-LC-MS/MS) reference method. Methods: The intra-batch precision, inter-batch precision, accuracy, and linear range of four homocysteine detection systems were evaluated. The ID-LC-MS/MS reference method was used to evaluate the comparability and accuracy of fresh frozen serum samples in four different detection systems of homocysteine. The ID-LC-MS/MS reference method is used to assign samples as calibrators to calibrate each system. The variation and deviation of fresh serum samples between different systems before and after calibration were compared. Results: The intra-batch imprecision of the four detection systems was less than 5%, and the coefficient of variation of inter-batch imprecision was less than 6.7%. The precision met the clinical requirements. Before calibration, the results measured by detection system 2 are consistent with the ID-LC-MS/MS reference method, which meets the requirements of accuracy verification. The regression equation of R² = 0.975 in the regression equation of linear analysis of the four systems, the linearity of the four detection systems is good in the range of evaluation concentration, and all of them can meet the declared linear range. The absolute average bias of fresh serum measured by the four detection systems after calibration decreased from 3.76 µmol/L, 0.96 µmol/L, 1.30 µmol/L, -1.56 µmol/L to 0.31 µmol/L, 0.28 µmol/L, 0.4 µmol/L, 0.40 µmol/L, respectively. The relative average bias decreased from 22.6%, 7.50%, 11.0% and -8.50% to 1.98%, 1.78%, 2.59%, 2.34%, respectively. After calibration, the slope and intercept of the regression curve of the fresh serum measured by the four detection systems and the reference method are closer to 1 and 0 than before calibration. Conclusions: The precision, reference interval, and linear evaluation of the four detection systems are good. The ID-LC-MS/MS reference method assigning fresh frozen serum samples as calibrators can improve the accuracy and comparability of the results of different detection systems. [ABSTRACT FROM AUTHOR]

The aims of this study were to determine the concentrations and elemental composition of PM10 in the village of Kotórz Mały (Poland), to analyse their seasonal variability, to determine the sources of pollutant emissions and to compare the consistency of the results obtained using different methods. Sampling and weather condition measurements were carried out in the winter (January–February) and spring (April) of 2019. Two combinations of different techniques were used to examine PM10 concentrations and their chemical composition: gravimetric method + atomic absorption spectrometry (GM+AAS) and continuous particle monitor + energy dispersive X-ray fluorescence (CPM+EDXRF). In winter, the average concentrations of PM10 measured by the GM and CPM were similar (GM 44.3 µg/m3; CPM 34.0 µg/m3), while in spring they were clearly different (GM 49.5 µg/m3; CPM 29.8 µg/m3). Both AAS and EDXRF proved that in both seasons, Ca, K and Fe had the highest shares in the PM10 mass. In the case of the lowest shares, the indications of the two methods were slightly different. Factor analysis indicated that air quality in the receptor was determined by soil erosion, coal and burning biomass, and the combustion of fuels in car engines; in the spring, air quality was also affected by gardening activities.

Nitric oxide (NO) and its by-products are important biological signals in human physiology and pathology particularly in the vascular and immune systems. Thus, in situ determination of the NO-related molecule (NOx) levels using embedded sensors is of high importance particularly in the context of cellular biocompatibility testing. However, NOx analytical reference method dedicated to the evaluation of biomaterial biocompatibility testing is lacking. Herein, we demonstrate a PAPA-NONOate-based reference method for the calibration of NOx sensors. After, the validation of this reference method and its potentialities were demonstrated for the detection of the oxidative stress-related NO secretion of vascular endothelial cells in a 3D tissue issued from 3D printing. Such NOx detection method can be an integral part of cell response to biomaterials. [ABSTRACT FROM AUTHOR]

Several methods are used worldwide for antibiotic susceptibility testing (AST) for the Mycobacterium tuberculosis complex (MTBC). The variability in the results obtained with these methods hampers setting epidemiological cut-off (ECOFF) values and clinical breakpoints according to EUCAST guidelines. Methods for susceptibility testing and determination of the minimal inhibitory concentrations (MICs) need to be standardized for MTBC isolates for old and new agents. Our objective was to establish a standardized reference method for MIC determination for MTBC. The EUCAST antimycobacterial susceptibility testing subcommittee (AMST) compared protocols of MIC determination with regard to medium, inoculum preparation, antituberculous agent preparation, incubation, reading of the results and interpretation. The EUCAST reference method of MIC determination for MTBC is the broth microdilution method in Middlebrook 7H9-10% OADC medium. The final inoculum is a 105 CFU/mL suspension, obtained from a 10−2 dilution of a 0.5 McFarland suspension prepared after vortexing bacterial colonies with glass beads before suspending them in sterile water. The culture is maintained in a U-shaped 96-well polystyrene microtitre sterile plate with a lid incubated at 36° ± 1°C. Reading is done using an inverted mirror as soon as the 1:100 diluted control (i.e. 103 CFU/mL suspension) shows visual growth. The MIC, expressed in mg/L, is the lowest concentration that inhibits visual growth. Mycobacterium tuberculosis H37Rv ATCC 27294 is used as the reference strain and its targeted MIC values are within the range 0.03–0.12 for isoniazid, 0.12–0.5 for levofloxacin and 0.25–1 mg/L for amikacin. The EUCAST reference method for MTBC was endorsed by EUCAST after public consultation and will from now on be used to define EUCAST ECOFFs and clinical breakpoints. This reference method is not primarily intended to be used under routine conditions and the AST methods will need to be calibrated against this reference method to be used with EUCAST breakpoints. [ABSTRACT FROM AUTHOR]

Various methods have been developed to detect the presence of contamination with Coliforms and E. coli in foods. The pour plate technique using VRBA medium is confirmed as a standard method in Iran. The biggest disadvantage of thismethod is the need to spend a lot of time, high volume of laboratory operations, multiple stages and ultimately long time to achieve the results. Today, due to the mass productionof various foodstuffs, the need for faster methods with high sensitivity to control the quality of food is necessary for the responsible oversight centers. The use of chromogenic medias is also one of the fastest diagnostic methods that have been developed. According to this matter,a comparative study was considered from the results of application of three chromogenic media and reference method in food quality control. Totally 100 samples of foodstuffs were evaluated for contamination to Coliform and E.coli using standard method and three chromogenic medias. Based on the obtained results, 86, 79, 85 and 80 samples were contaminated to Coliform using the standard method, Coliform Agar ES, ChromAgar ECC and Rapid E.coli 2/Agar respectively. Also, using four mentioned methods, contamination to E.coli was reported at 66, 80, 84 and 80, respectively. Cochrane test showed that there was no significant difference between the four methods in Coliform diagnosis (p>0.05). However, four methods did not have the same function in the detection of E. coli so that the chromogenic methods showed significant difference with the standard method (p< 0/001). But there was no significant difference between these chromogenic methods in detecting E.coli (p>0.05). According to the statistical analysis of present study, three chromogenic medias can be used instead of the standard method for the detection of Coliform, but the use of these chromogenic medias is not recommended for the identification of E.coli. [ABSTRACT FROM AUTHOR]

• In this work, an alternative system was developed using ICP-MS, samples were diluted directly using a 0.3% nitric acid solution. Standards addition and an internal standard, germanium (Ge), were used to improve the accuracy of the method. We also used He gas to eliminate polyatomic ion interferences for Na and Ge. The analytical performances of the method as well as methods comparison regarding sodium assays have been tested. The new ICP-MS method proved to be accurate, reliable, simple, and fast and may be used as a candidate reference method for setting target values in the standardization of serum sodium measurements. Levels of serum sodium (Na) are widely determined in clinical laboratories. Accordingly, sodium quantification must be performed using reliable methods. Herein are reported the results of the evaluation of a new inductively coupled plasma mass spectrometry (ICP-MS) method for sodium quantification. Serum samples were diluted 100 × by 0.3% ultrapure nitric acid, and germanium (Ge) was used as an internal standard. Sodium calibration solutions with different concentrations were added to serum matrix solutions. The serum sodium concentration was calculated according to the standards addition method. The analytical performance of the method, as well as a comparison with other sodium method, was investigated. The correlation coefficients (r) between the measured Na/Ge ratios and the analyte concentration ratios were all > 0.9999. Intra- and between-assay coefficients of variation (CVs) were < 0.64% and < 0.57%, respectively, and the total CV was < 0.67%. The trueness of the method was verified by measuring a certified reference material, SRM 956d. The new ICP-MS method was compared with the 2017 and 2018 External Quality Assessment Scheme for Reference Laboratories in Laboratory Medicine (RELA). The results were well correlated with those obtained by the routine indirect ion selective electrode (ISE) method: sodium (ICP-MS, mmol/L) = 0.9895 × sodium (ISE, mmol/L) + 1.3049 (r = 0.9914, n = 40). The mean deviation between the results of the ICP-MS method and the indirect ISE method was –0.15%. The new ICP-MS method proved to be accurate, reliable, simple, and fast and may be used as a candidate reference method for setting target values in the standardization of serum sodium measurements. [ABSTRACT FROM AUTHOR]

Value addition of fresh tender jackfruit (Artocarpus heterophyllus L.) for vegetable purpose has gained much popularity due to its inherent nutritional and health benefits. For industries involved in value addition of tender jackfruit, rapid characterization of raw material is essential for screening and routine quality evaluation. But, conventional reference methods of quality evaluation are not suitable as they involve the use of chemicals, expensive, laborious and time consuming subject to the number of samples to be analyzed. As a promising alternative, the present study examined the performance of near-infrared spectroscopy (NIRS) as a novel approach to estimate pH, total soluble solid, titrable acidity, firmness and toughness of tender jackfruit. Partial least square regression (PLSR) models were used to establish linkage between reflectance spectra (1100-2450 nm) and quality attributes of fresh tender jackfruit. Based on residual prediction deviation (RPD) criteria, accuracy of PLSR model of titrable acidity was noted to be excellent (RPD=3.96) while good estimation was possible in case of firmness-tendril (RPD=2.61). Accuracy level suitable for coarse quantitative estimation (RPD=2.12) was noted in case of total soluble solids. The PLSR models of all other attributes were found to be capable of discriminating their low and high values (1.5

Background: Total haemoglobin (Hb) concentration in blood belongs to the most requested measurands, and the HiCN method (hemiglobincyanide) is accepted as a reference. Although the reaction principle is clearly characterised, measurement conditions and settings are not consistently defined, some of them influencing the results. An improvement of standardisation is the object. Methods: After method optimization, measurement results between different calibration laboratories (CL) were compared with each other and also with results of the National Metrology Institute of Germany (PTB), with target values of certified reference material, within the RELA scheme, and to >1500 results from routine laboratories. Results: Overall deviations between three CLs were ≤0.5% (n = 24 samples) in a measurement range of 20 g/L to 300 g/L. A CV of 0.4% was determined in pooled blood (1 year long-term imprecision, 99.0%–101.1% recovery of the mean). For selected measurements (n = 4 samples) the PTB participated without significant differences to three CLs, and no significant differences were observed comparing CLs to certified values of reference materials. The expanded measurement uncertainty (probability 95%) was estimated as 1.1%. Conclusions: A reference measuring system, comprising measuring instruments and other devices, including reagents and supply, to generate reference measurement values for total Hb concentration of high accuracy and low measurement uncertainty is presented. Measurement parameters are investigated and defined. The reference measuring system is ready to offer service to EQA providers and to the IVD industry for certifying control materials or calibrators. [ABSTRACT FROM AUTHOR]

Accurate and precise cortisol measurements are requisite for ensuring appropriate diagnosis and management of diseases related with adrenal or pituitary gland disorders. Prompted by the needs in characterization of certified reference materials and quality assurance for serum cortisol measurements, we developed and evaluated a highly reliable measurement procedure based on isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) combined with dextran sulfate-Mg2+ precipitation as the sample pretreatment. An appropriate amount of serum was accurately weighed and spiked with the isotope labelled internal standard. After precipitation, massive lipids and lipoproteins were removed from serum matrix. The clear supernatant was transferred and extracted with ethyl acetate-hexane solution. The cortisol was analyzed with LC-MS/MS in positive electrospray ionization mode. The within-run and total coefficient of variations (CVs) ranged from 0.3 to 0.6% and 0.7 to 1.2%, respectively, for a concentration range of 76.30 to 768.04 nmol/L. A regression comparison of the results obtained by the present method and the certified values of ERM-DA451 showed agreement with no statistical difference (Y = 1.0092 X-0.7455; 95% CI for the slope, 0.9940 to 1.0212; 95% CI for the intercept, − 3.6575 to 2.6390, r2 = 0.999). All structural analogs of cortisol tested were well resolved from cortisol in 12 min on a phenyl ligand column under an isocratic elution. The limit of quantification was estimated to 5 pg cortisol in absolute amount. This method is accurate and simple and can be served as a candidate reference measurement procedure in establishment of serum cortisol reference system. [ABSTRACT FROM AUTHOR]

A standardized reference method is needed to accurately and precisely measure urine-formed elements (UFEs; red blood cells [RBCs], white blood cells [WBCs], and squamous epithelial cells [sECs]). We compared the results from a standard method with those from an automated analyzer. Trained technicians used standardized bright-field microscopy of fresh non-centrifuged urine samples, and disposable 1 µl chambers. Fifteen experienced technicians from 5 hospitals (3 per hospital) each performed 6 manual counts of 10 different native urine samples using a manual chamber and standard methods. The sEC counts were at least 50/µL, and the coefficient of variation (CV) was less than 14%; the RBC and WBC counts were at least 200/µL and the CVs were less than 7%. The same samples were also analyzed 6 times using automated analyzers. The means, CVs, and biases were determined. The median CVs for the manual measurements were 6.4% (WBCs), 6.6% (RBCs), and 12.7% (sECs). The CVs of the automated analyzer were 4.7% (WBCs), 5.6% (RBCs), and 9.2% (sECs). Biases between the automated and manual methods were -2.9% to 5.0%(WBCs), -0.8% to 8.8% (RBCs) and -2.8% to 9.4% (sECs). The count mean values and expanded uncertainties of these counts were (224.5 ± 15.0) cells/µL, (234.2 ± 16.2) cells/µL, and (61.5 ± 7.9) cells/µL, respectively. The standardized manual method for measuring UFEs had high precision and accuracy, making it a suitable reference method. Use of this reference method to calibrate an automated analyzer improved the accuracy of automated analysis. [ABSTRACT FROM AUTHOR]

To efficiently transport pipeline crude oils, obtaining the saturated vapor pressure of oils is very important. In this work, we sampled five pipeline crude oils from one domestic oilfield, and then by using the reference method, the saturated vapor pressure of these five oils were measured under the temperatures of 37.8 ℃,45.0 ℃,50.0 ℃,55.0 ℃ and 60.0 ℃. The experimental results showed that the saturated vapor pressure of pipeline crude oils increased rapidly with the increase of temperature. With the temperature increased from 37.8 ℃ to 60.0 ℃, the increments of saturated vapor pressures of all five samples were more than 80%. Besides temperature, the concentration of components with the carbon number from 7 to 15 in the oil is another significant factor which affects the saturated vapor pressure of pipeline crude oils. The higher concentration of these components is, the lower saturated vapor pressure of pipeline crude oils has. Furthermore, a correlation for predicting the saturated vapor pressure of pipeline crude oils of the aimed oil field was developed, in which both the temperature and basic physical properties of the oil were considered. The simulated results agreed well with the experimental results. [ABSTRACT FROM AUTHOR]

BACKGROUND: The use of liquid whole egg (LWE) in the food industry as a substitute for shell eggs has been on the increase lately. Since the composition of LWE can easily be changed, determination of protein, lipid, moisture and total soluble solid (TSS) contents of LWE has also gained importance. Traditional methods usually require more time and effort, and the use of toxic chemicals for sample preparation; hence more efficient techniques (faster, cheaper and more reliable) are needed. In this regard, a novel technique that determines LWE components using attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy with partial least squares regression (PLS) is presented in this study. RESULTS: The actual values of LWE components were determined by applying reference methods. The accuracy of the PLS model was demonstrated by comparing the obtained predictions with the actual values of the components. High coefficients of determination values, which are 0.950, 0.992, 0.994 and 0.972, were achieved for protein, lipid, moisture, and TSS validation datasets, respectively. The error values, namely RMSEC, RMSECV and RMSEP, were obtained in the ranges 0.404–0.978, 0.57–1.82 and 0.83–1.84, respectively. CONCLUSIONS: ATR‐FTIR spectroscopy coupled with chemometrics can provide a rapid and sensitive method for quality control of liquid egg composition. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Measurement of serum progesterone is important in determining ovarian function. Most progesterone measurements are performed with immunoassays and results are often variable. Standardization of the measurements requires a reliable reference method. An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method for the measurement of serum progesterone was developed. Serum samples were spiked with 13C3-progesterone, extracted with a three-step liquid-liquid extraction, and analyzed by LC/MS/MS. A bracketing calibration was used for the analysis and samples were prepared gravimetrically. The developed method showed intra-run and total relative standard deviations (RSDs) of 0.50~0.58% and 0.71~1.33%, respectively. The analytical recoveries were 99.08~101.50%. Measurement results on certified reference materials obtained with this method agreed with the certified values within the stated measurement uncertainties. The method was applied to evaluate immunoassays through split-sample comparisons. A panel of 48 fresh frozen individual samples were measured with the ID-LC/MS/MS method, and six immunoassays and results were compared. Significant calibration biases and sample-specific deviations were observed on some of the immunoassays. [ABSTRACT FROM AUTHOR]

Quantitative chemical analysis of airborne particulate matter (PM) is vital for the understanding of health effects in indoor and outdoor environments, as well as for enforcing EU air quality regulations. Typically, airborne particles are sampled over long time periods on filters, followed by lab-based analysis, e.g., with inductively coupled plasma mass spectrometry (ICP-MS). During the EURAMET EMPIR AEROMET project, cascade impactor aerosol sampling is combined for the first time with on-site total reflection X-ray fluorescence (TXRF) spectroscopy to develop a tool for quantifying particle element compositions within short time intervals and even on-site. This makes variations of aerosol chemistry observable with time resolution only a few hours and with good size resolution in the PM10 range. The study investigates the proof of principles of this methodological approach. Acrylic discs and silicon wafers are shown to be suitable impactor carriers with sufficiently smooth and clean surfaces, and a non-destructive elemental mass concentration measurement with a lower limit of detection around 10 pg/m3 could be achieved. We demonstrate the traceability of field TXRF measurements to a radiometrically calibrated TXRF reference, and the results from both analytical methods correspond satisfactorily.

A candidate reference measurement procedure (RMP) for measurement of unconjugated estriol in human serum has been developed and validated. The proposed method is highly reliable and uses isotope dilution coupled with liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) and requires no derivatization. An appropriate amount of serum was accurately weighed and spiked with an isotopically labeled internal standard. Unconjugated estriol and its internal standard were extracted from serum matrix using liquid-liquid extraction prior to reversed-phase LC-MS/MS. Calibrator bracketing was used to give higher specificity and accuracy for assigning serum level. The accuracy of the candidate RMP was validated by split-sample comparison to established RMPs. The lowest limit of detection (LLoD) and lowest limit of quantification (LLoQ) for developed RMP was estimated to be 0.14 nmol/L and 0.35 nmol/L, respectively. Both intra- and inter-assay imprecisions were ≤2.19% at 1.39, 17.34 and 69.35 nmol/L, respectively. Recoveries were 98.54% to 100.34% and linear response ranged from 0.35 to 173.38 nmol/L. No interference was observed. Biases were 5.6% and 2.8% against the targets of RELA2015A (3.87 nmol/L) and RELA2015B (40.62 nmol/L), respectively. Moreover, the candidate RMP was successfully applied to measure level of unconjugated estriol in serum samples of pregnant women (n = 3) and compared with two immunoassays in clinical laboratory. Our developed method is simple, accurate, and can be used as a candidate RMP to determine total unconjugated estriol level in human serum. Further improvement of certain immunoassays in accuracy and precision is needed.Selected ion chromatograms by LC-MS/MS using a C18 column for uE3 from a serum sample [ABSTRACT FROM AUTHOR]

We estimated the measurement uncertainty (MU) of platelet concentration measured using the Sysmex XN system with two reference platelet counting methods described by DIN 58932-5 (PTB method) and the International Council for Standardization in Haematology (ICSH method). Ten blood samples were used to estimate and compare the MU of the XN system, and 30 samples were used to compare the methods. The standard uncertainty of the reference method was significantly higher for the ICSH method; the PTB method showed higher platelet concentrations than the ICSH method. When applying different methods with the XN system, optic counting showed higher MU compared to the other methods. There was good correlation among the two reference methods and three automated platelet-counting methods. We evaluated the MU in platelet concentrations measured using an automated hematology analyzer. Our results suggest that using the PTB method for calculating MU of the automated hematology analyzer is superior to the ICSH method because of its lower standard uncertainty. [ABSTRACT FROM AUTHOR]

The milk analyse result reliability is important for assurance of foodstuff chain quality. There are more direct and indirect methods for milk composition measurement (fat (F), protein (P), lactose (L) and solids non fat (SNF) content). The goal was to evaluate some reference and routine milk analytical procedures on result basis. The direct reference analyses were: F, fat content (Röse–Gottlieb method); P, crude protein content (Kjeldahl method); L, lactose (monohydrate, polarimetric method); SNF, solids non fat (gravimetric method). F, P, L and SNF were determined also by various indirect methods: – MIR (infrared (IR) technology with optical filters), 7 instruments in 4 labs; – MIR–FT (IR spectroscopy with Fourier’s transformations), 10 in 6; – ultrasonic method (UM), 3 in 1; – analysis by the blue and red box (BRB), 1 v 1. There were used 10 reference milk samples. Coefficient of determination (R2), correlation coefficient (r) and standard deviation of the mean of individual differences (MDsd, for n) were evaluated. All correlations (r; for all indirect and alternative methods and all milk components) were significant (P ≤ 0.001). MIR and MIR–FT (conventional) methods explained considerably higher proportion of the variability in reference results than the UM and BRB methods (alternative). All r average values (x minus 1.64 × sd for 95% confidence interval) can be used as standards for calibration quality evaluation (MIR, MIR–FT, UM and BRB): – for F 0.997, 0.997, 0.99 and 0.995; – for P 0.986, 0.981, 0.828 and 0.864; – for L 0.968, 0.871, 0.705 and 0.761; – for SNF 0.992, 0.993, 0.911 and 0.872. Similarly ​MDsd (x plus 1.64 × sd): – for F 0.071, 0.068, 0.132 and 0.101%; – for P 0.051, 0.054, 0.202 and 0.14%; – for L 0.037, 0.074, 0.113 and 0.11%; – for SNF 0.052, 0.068, 0.141 and 0.204.

Blood-based indicators that are used in the assessment of iron status are assumed to be accurate. In practice, inaccuracies in these measurements exist and stem from bias and variability. For example, the analytic variability of serum ferritin measurements across laboratories is very high (≥15%), which increases the rate of misclassification in clinical and epidemiologic studies. The procedures that are used in laboratory medicine to minimize bias and variability could be used effectively in clinical research studies, particularly in the evaluation of iron deficiency and its associated anemia in pregnancy and early childhood and in characterizing states of iron repletion and excess. The harmonization and standardization of traditional and novel bioindicators of iron status will allow results from clinical studies to be more meaningfully translated into clinical practice by providing a firm foundation for clinical laboratories to set appropriate cutoffs. In addition, proficiency testing monitors the performance of the methods over time. It is important that measures of iron status be evaluated, validated, and performed in a manner that is consistent with standard procedures in laboratory medicine. [ABSTRACT FROM AUTHOR]

Background: Potassium is an important serum ion that is frequently assayed in clinical laboratories. Quality assurance requires reference methods; thus, the establishment of a candidate reference method for serum potassium measurements is important. Methods: An inductively coupled plasma mass spectrometry (ICP-MS) method was developed. Serum samples were gravimetrically spiked with an aluminum internal standard, digested with 69% ultrapure nitric acid, and diluted to the required concentration. The 39K/27Al ratios were measured by ICP-MS in hydrogen mode. The method was calibrated using 5% nitric acid matrix calibrators, and the calibration function was established using the bracketing method. Results: The correlation coefficients between the measured 39K/27Al ratios and the analyte concentration ratios were >0.9999. The coefficients of variation were 0.40%, 0.68%, and 0.22% for the three serum samples, and the analytical recovery was 99.8%. The accuracy of the measurement was also verified by measuring certified reference materials, SRM909b and SRM956b. Comparison with the ion selective electrode routine method and international inter-laboratory comparisons gave satisfied results. Conclusions: The new ICP-MS method is specific, precise, simple, and low-cost, and it may be used as a candidate reference method for standardizing serum potassium measurements. [ABSTRACT FROM AUTHOR]

Introduction To provide target values for the manufacturers' survey of the Japanese Society for Laboratory Hematology ( JSLH), accurate standard data from healthy volunteers were needed for the five-part differential leukocyte count. To obtain such data, JSLH required an antibody panel that achieved high specificity (particularly for mononuclear cells) using simple gating procedures. We developed a flow cytometric method for determining the differential leukocyte count ( JSLH-Diff) and validated it by comparison with the flow cytometric differential leukocyte count of the International Council for Standardization in Haematology ( ICSH-Diff) and the manual differential count obtained by microscopy (Manual-Diff). Methods First, the reference laboratory performed an imprecision study of JSLH-Diff and ICSH-Diff, as well as performing comparison among JSLH-Diff, Manual-Diff, and ICSH-Diff. Then two reference laboratories and seven participating laboratories performed imprecision and accuracy studies of JSLH-Diff, Manual-Diff, and ICSH-Diff. Simultaneously, six manufacturers' laboratories provided their own representative values by using automated hematology analyzers. Results The precision of both JSLH-Diff and ICSH-Diff methods was adequate. Comparison by the reference laboratory showed that all correlation coefficients, slopes and intercepts obtained by the JSLH-Diff, ICSH-Diff, and Manual-Diff methods conformed to the criteria. When the imprecision and accuracy of JSLH-Diff were assessed at seven laboratories, the CV% for lymphocytes, neutrophils, monocytes, eosinophils, and basophils was 0.5~0.9%, 0.3~0.7%, 1.7~2.6%, 3.0~7.9%, and 3.8~10.4%, respectively. More than 99% of CD45 positive leukocytes were identified as normal leukocytes by JSLH-Diff. Conclusions When JSLH-Diff method were validated by comparison with Manual-Diff and ICSH-Diff, JSLH-Diff showed good performance as a reference method. [ABSTRACT FROM AUTHOR]

The total haemoglobin (Hb) concentration in blood is one of the most frequently measured analytes in clinical medicine because of its significance for evaluating the health state of a human. The spectrophotometric cyanmethaemoglobin (HiCN) method is the internationally accepted conventional reference method to determine this biomarker. It is frequently used in clinical routine diagnostics but is not traceable to the International System of Units and thus does not meet highest metrological demands. A further critical issue is the toxicity of the necessary potassium cyanide. Different methods to solve these problems are reported here. They all were validated against the HiCN method in an interlaboratory comparison by measuring the total Hb concentration present in the certified reference material JCCRM 912-2M. Methods considered were the spectrophotometric alkaline haematin detergent (AHD) method as well as several isotope dilution (ID)-based approaches. The latter include inductively coupled plasma mass spectrometry (ICP-MS), species-specific (SS) ICP-MS, organic MS and Raman spectrometry. [ABSTRACT FROM AUTHOR]